Tomato Seeds Research Articles

Valorisation of tomato seeds: investigating the effects of defatting on the physico-chemical, rheological, structural and techno-functional properties

Valorisation of tomato seeds: investigating the effects of defatting on the physico-chemical, rheological, structural and techno-functional properties

Characterisation of the Endophytic and Rhizospheric Bacillus licheniformis Strains Isolated from Sweet Potato with Plant Growth-Promoting and Yield Enhancing Potential

The primary aim of the present study was to identify bacterial isolates with yield-enhancing potential for application as biofertilisers in the cultivation of sweet potato. Therefore, endophytic and rhizospheric strains were isolated from sweet potato plantations in Hungary to identify bacterial strains with plant growth-promoting and antifungal potential. In total, seven Bacillus licheniformis strains were identified and subjected to detailed ecophysiological investigations. Experiments have been conducted to investigate the tolerance of selected strains to different limiting factors such as pH, temperature, and water activity, which affect survivability in various agricultural environments. The majority of tested B. licheniformis strains exhibited plant growth-promoting potential (e.g., production of indole-3-acetic acid up to 40.42 μg mL−1, production of ammonia up to 0.87 mg mL−1, phosphorus solubilising activity, siderophore production), with two strains (SZMC 27713 and SZMC 27715) demonstrating inhibitory activity (ranging between 7% and 38%) against plant pathogenic fungi prevalent in sweet potato cultivation. Furthermore, strain SZMC 27715 induced accelerated germination and a significantly higher germination rate in tomato seeds compared to the control. In a field study, it was observed that strain SZMC 27715 had a potent yield enhancing effect in sweet potato, where a significant yield per plant increase was observed in all treatments (1.13, 1.09 and 1.40 kg) compared to the control plants (0.92 kg). The highest yield per plant was observed when the cuttings were soaked combined with two additional foliar treatments. To the best of our knowledge, this is the first report of the successful utilisation of the B. licheniformis strain as a biofertiliser for yield enhancement in sweet potato cultivation. Based on our results, strain SZMC 27715 has potential for application as a biofertiliser in sweet potato cultivation either as a standalone option or in a microbial consortium.

Management of seed borne ralstonia solanacearum in brinjal (Solanum melongena L.) and tomato (Lycopersicon esculentum Mill.)

Total of 165 bacterial isolates of Ralstonia solanacearum were collected from different seed samples of tomato and brinjal in various seed sources and 22 isolates were tested to find out the management tools among different management approaches. Hundred percent reduction of bacterial incidence was found with Gentamicin (0.1, 0.05%), Erythromycin (0.1, 0.05%) and Doxycycline (0.1%) over control in both brinjal and tomato treated seeds in nutrient agar medium. Seed treatment with BAU-Biofungicide (3%) exhibited 83.61% decreases of bacterial incidence over control in tomato and 90.28% reduction in brinjal seeds. Garlic also showed better performance in controlling R. solanacearum among the plant extracts. Antibiotic sensitivity test revealed that maximum number of isolates of R. solanacearum was found to be sensitive to Gentamicin and Erythromycin, and the highest number of isolate of R. solanacearum of tomato and brinjal seeds marked resistant to Doxycycline. Higher germination 40.38% was achieved over control in tomato seed and 26.67% germination was in brinjal seed when the seeds were treated with BAU-Biofungicide (3%). Among all the treatments, BAU-Biofungicide (3%) also resulted in the highest increase of vigor index (77.36%) in tomato and brinjal seed with an increase of 69.91% over untreated control. Bangladesh J. Bot. 53(1): 173-183, 2024 (March)

The Effects of Oxygen Availability in the Seed Container during Storage on Seed Germination in Tomato, Onion, Cabbage, and Marrow Seeds

This research was conducted to test the effect of oxygen content (low O2, high O2, air) during hermetic seed storage at 20±2°C over 8 and 12 months on seed germination and seedling root and shoot length in tomato, onion, cabbage, and marrow seeds. Samples with low oxygen storage had higher seed germination as well as longer root and shoot lengths than both control and high oxygen storage. When the storage period extended from 8 to 12 months, the germination percentages also reduced. However, these results varied among the species. The greatest advantage of low oxygen storage was obtained in tomatoes, which exhibited 15% and 9% higher germination compared to the control after 8 and 12 months of storage, respectively. The longest root and shoot lengths of 6.4 cm and 11.6 cm, respectively, were obtained from the low oxygen storage treatments. A similar positive effect of low oxygen storage was observed in onion and cabbage seeds but not in marrows. Results indicated that oxygen level in the packets during storage can be an effective component to maintain high seed germination and seedling growth potential (seed vigour). The difference in the effect on different species is a matter of further research.

Methodology of the accelerated aging test in tiny tomato seeds (solanum lycopersicum var. cerasiforme)

The objective of this study was to study whether the variations in the performance of the accelerated aging test, in terms of exposure time and temperature involved in the test methodology, performed in the traditional way or in saturated salt solution, would result in an efficient combination to evaluate the physiological quality of seeds tiny tomato (Solanum lycopersicum var. cerasiforme). The seeds were submitted to the tests of total germination, germination speed index, first germination count, substrate emergence, seedling length, seedling dry matter, cold test, electrical conductivity and variations in the conduction of the accelerated aging test. The treatments (36, 38, 40 and 42 ºC) x exposure time (24, 36, 48 and 72 hours) x procedures (traditional and saline) were used, with four replications each lot. The averages were compared by the Tukey test at 5% probability. The simple correlation coefficient (r) between the accelerated aging test results and the emergence test of substrate seedlings was also determined. The traditional accelerated aging test in the combinations of 24 hours at 36 °C and the accelerated aging test with saline in the combinations of 72 hours at 36 °C showed sensitivity for the evaluation of the physiological potential of tiny tomato seeds. For both accelerated aging tests, the temperature of 36 °C was efficient for the evaluation of the physiological potential of tiny tomato seeds.

Supercritical CO2 Treatment to Modify Techno-Functional Properties of Proteins Extracted from Tomato Seeds.

Tomato seeds are a rich source of protein that can be utilized for various industrial food purposes. This study delves into the effects of using supercritical CO2 (scCO2) on the structure and techno-functional properties of proteins extracted from defatted tomato seeds. The defatted meal was obtained using hexane (TSMH) and scCO2 (TSMC), and proteins were extracted using water (PEWH and PEWC) and saline solution (PESH and PESC). The results showed that scCO2 treatment significantly improved the techno-functional properties of protein extracts, such as oil-holding capacity and foaming capacity (especially for PEWC). Moreover, emulsifying capacity and stability were enhanced for PEWC and PESC, ranging between 4.8 and 46.7% and 11.3 and 96.3%, respectively. This was made possible by the changes in helix structure content induced by scCO2 treatment, which increased for PEWC (5.2%) and decreased for PESC (8.0%). Additionally, 2D electrophoresis revealed that scCO2 hydrolyzed alkaline proteins in the extracts. These findings demonstrate the potential of scCO2 treatment in producing modified proteins for food applications.

Biological Control of Pseudomonas syringae in Tomato Using Filtrates and Extracts Produced by Alternaria leptinellae

Endophytic fungi offer promising alternatives for sustainable plant disease management strategies, often through the production of bioactive secondary metabolites. This study investigated the biocontrol potential of filtrates and extracts, produced under controlled conditions, from Alternaria leptinellae E138 against Pseudomonas syringae in tomato plants under greenhouse conditions. To understand the main mechanisms involved in biocontrol, the direct inhibition of bacterial growth and disruption of quorum sensing activity caused by metabolites were studied in vitro, as well as indirect mechanisms, such as their capacity to produce phytohormone-like substances, nutrient mobilization, and antioxidant activity, which can enhance plant growth and fitness. Moreover, a mass spectrometry analysis was used to tentatively identify the secondary metabolites present in the extract with antimicrobial properties, which could explain the biocontrol effects observed. Mycopriming assays, involving the direct treatment of tomato seeds with the fungal A. leptinellae E138 extracts, produced increased germination rates and seedling vigor in tomato seeds. As another treatment, postemergence application of the extracts in greenhouse conditions significantly improved plant health and resulted in a 41% decrease in disease severity. Overall, this study underscores the potential of A. leptinellae E138 extract as a plant growth promoter with biocontrol capabilities, offering promising avenues for sustainable plant disease management.

Phytotoxicity Assessment of Different Animal Manure on Selected Vegetable Crops in Kashere Community, Gombe State, Nigeria

The present study evaluated the phytotoxicity effect of poultry, goat and cow manure on Okra, Tomato and Pepper vegetables using appropriate standard methods. In the current study, of the three different manure collected and used on the three vegetable crops, GI value of <50% was recorded on Okra and Pepper seeds mounted on PM medium (48.51% and 41.36% respectively), GI value of between 50% and 80% was recorded on Okra, Tomato and Pepper seeds mounted on GM medium (64.76%, 79.77% and 73.70% respectively) also Pepper seeds mounted on CM medium (76.48%) and Tomato seeds mounted on PM medium (75.41%) while GI Value of >80% was observed on Okra and Tomato Seeds mounted on a CM medium (81.63% and 94.10% respectively). Overall result of all the animal manure evaluated, poultry manures was phytotoxic on okra and pepper seed and moderately phytotoxic on Tomato seed based on the plant bioassay evaluated. It is possible that other chemicals that were not analyzed in this study could potentially be responsible for the phytotoxic effects of poultry manure on the vegetable seeds, indicating that some curing in the form of composting or vermicomposting may be necessary to degrade or reduce the presence of phytotoxic compounds in the poultry manure used for the study before use as soil amendments and thus would help to render the resultant end product environmentally safer.

Impact of seed priming with Selenium nanoparticles on germination and seedlings growth of tomato

Poor germination and seedlings growth can lead to significant economic losses for farmers, therefore, sustainable agricultural strategies to improve germination and early growth of crops are urgently needed. The objective of this work was to evaluate selenium nanoparticles (Se NPs) as nanopriming agents for tomato (Solanum lycopersicum) seeds germinated without stress conditions in both trays and Petri dishes. Germination quality, seedlings growth, synergism-antagonism of Se with other elements, and fate of Se NPs, were determined as function of different Se NPs concentrations (1, 10 and 50 ppm). Results indicated that the germination rate in Petri dishes improved with 10 ppm, while germination trays presented the best results at 1 ppm, increasing by 10 and 32.5%, respectively. Therefore, seedlings growth was measured only in germination trays. Proline content decreased up to 22.19% with 10 ppm, while for same treatment, the total antioxidant capacity (TAC) and total chlorophyll content increased up to 38.97% and 21.28%, respectively. Antagonisms between Se with Mg, K, Mn, Zn, Fe, Cu and Mo in the seed were confirmed. In the case of seedlings, the N content decreased as the Se content increased. Transmission Electron Microscopy (TEM) imaging confirmed that Se NPs surrounded the plastids of the seed cells. By this finding, it can be inferred that Se NPs can reach the embryo, which is supported by the antagonism of Se with important nutrients involved in embryogenesis, such as K, Mg and Fe, and resulted in a better germination quality. Moreover, the positive effect of Se NPs on total chlorophyll and TAC, and the negative correlation with proline content with Se content in the seed, can be explained by Se NPs interactions with proplastids and other organelles within the cells, resulting with the highest length and fresh weight when seeds were exposed to 1 ppm.

Investigating the synergistic impact of ozonated water irrigation and organic fertilization on tomato growth

This study presents the outcomes of an experimental investigation aimed at evaluating the combined impact of irrigating tomatoes with ozonated water and applying organic fertilization. The experiment was conducted in a greenhouse equipped with an innovative ozonated water generation system. Tomato seeds were planted in 240 pots of 2-liter volume, arranged in 16 rows with 15 pots each. Alongside the native greenhouse topsoil, three distinct substrate mixtures incorporating compost compositions of 10%, 20%, and 40% were examined. Regular irrigation, twice a week, was implemented using three varying concentrations of dissolved ozone in water (1, 2, and 3 ppm). Results obtained after approximately three months of cultivation unveiled an almost twofold increase in plant productivity with ozonated water irrigation. This effect was notably pronounced when utilizing the native topsoil and a substrate containing 10% compost, coupled with an ozone concentration of 2 ppm. Intriguingly, the use of ozonated water facilitated enhanced development of both aerial and root components of the tomato plants. Moreover, the study suggests that organic fertilization may not be necessary when irrigating with ozonated water, as comparable productivity was observed for both fertilized and non-fertilized soil substrates. Although physicochemical analyses indicated minimal alterations, the noticeable improvement in plant vitality underscores the positive influence of ozone.

Effect of Seed Spaceflight Storage on Tomato Fruit Quality and Peel/Pulp Mineral and Antioxidant Distribution

The spaceflight storage of seeds is known to cause mutations affecting both their quality and the mature plants originating from them. To study the effects of space stress, tomato seeds of two cultivars (Lotus and Autumn rhapsody) were subjected to half a year of storage at the International Space Station (ISS), and then, sown in a greenhouse to produce tomato fruits. The space-treated plants gave smaller fruits with a stable total yield not significantly different from that of the control plants. Space-treated tomatoes showed significantly higher levels of dry matter, dietary fiber, monosaccharides and citric and malic acids and lower values of oxalic acid compared to the control plants. The pulp of space-treated fruits had 1.44–1.70 times lower levels of carotenoids, while their peel contained a 1.27–1.90 times higher pigment amount compared to the control plants. No significant changes in the total antioxidant activity (AOA), photosynthetic pigments and phenolic (TP) and proline content were recorded in the fruits due to seed spaceflight storage. Contrarily, space-treated tomatoes showed decreased levels of Ca, Sr and Mo and increased Se both in the fruit pulp and peel. The concentration of Fe and especially Pb was lower in space-treated fruit pulp. Positive correlations between Se and dry matter, Ca and Sr, Ca and Co, Ca and Fe, and Cr and carotenoids, and negative correlations between Se and Mo, Se and K, and Mo and dry matter were recorded. The results indicate that seed stress caused by long-term spaceflight affects both the biochemical characteristics and mineral composition of tomato fruits and causes the peel/pulp redistribution of carotenoids as well as macro- and micro-elements, improving Se accumulation levels in the fruit peel.

Effects of Elicitation on Invitro Regeneration of two Tomato (Solanum lycopersicum L.) Cultivars in Tissue Culture

Exploring alternative avenues, in vitro culture emerges as a promising option for potential bioactive compound sources. However, compared to intact plants, only a few cultures demonstrate efficient synthesis of secondary metabolites. Elicitors have gained prominence as stress agents for enhancing in vitro micropropagation in specific tissues, organs, and cells. Recent advancements in plant tissue culture involve elicitors, opening new possibilities for in vitro production of crucial food crops. This research aimed to investigate the impact of three elicitors (Activane®, Micobiol®, and Stemicol®) on germination and in vitro multiplication of two tomato cultivars explants, employing both direct and indirect in vitro organogenesis. Among the texted elicitors, Micobiol® emerged as a successful elicitor, promoting optimal seed germination, survival, and 100% growth compared to the 80% in the control group. Further, Activane® exhibited a favourable induction response and achieved 96%, 95%, and 100% in weight and diameter of callus, yet various elicitor concentrations did not exert significant influence across treatments. In conclusion, an effective disinfection and in vitro implantation of tomato seeds ensured successful germination, promoting seedling survival and growth. Various elicitors positively impacted in vitro organogenesis, particularly in root induction, with higher survival percentages in acclimatized plants. The study guides future research on elicitor treatments for large-scale tomato in vitro propagation, emphasizing the need to identify optimal elicitor concentrations.

Seed Priming with Nanoencapsulated Gibberellic Acid Triggers Beneficial Morphophysiological and Biochemical Responses of Tomato Plants under Different Water Conditions

Water deficit (WD) promotes great losses in agriculture, and the development of new sustainable technologies to mitigate the effects of this stress on plants is essential. This study aimed to evaluate the morphophysiological and biochemical alterations induced by the priming of tomato seeds with different formulations in plants under field capacity and WD conditions. In the first experiment, the treatments consisted of nanoparticles of alginate/chitosan and chitosan/tripolyphosphate containing gibberellic acid (GA3) in different concentrations (0.5, 5, and 50 µg mL−1 GA3), in addition to control with deionized water. The alginate/chitosan (5 µg mL−1 GA3) provided the greatest gains in plant growth under field capacity. In addition, under WD this treatment reduced damage to photosystem II (−14%), stomatal conductance (−13%), and water loss (−38%) and increased the instantaneous carboxylation efficiency (+24%) and intrinsic water use efficiency (+12%). In the second experiment, the treatments were alginate/chitosan nanoparticles containing GA3 (NPGA3 5 µg mL−1), free GA3 (GA3 5 µg mL−1), nanoparticles without GA3 (NP), deionized water (WATER), and non-primed seeds (CONT). Under WD, GA3 and CONT maintained plant growth and lost water rapidly, reducing stomatal conductance (−87%) and net photosynthesis (−69%). In contrast, NPGA3 decreased leaf area (−44%) and increased root-to-shoot ratio (+39%) when compared to GA3, reducing water loss (−28%). Activation of protective mechanisms (e.g., superoxide dismutase and catalase activities) by WATER, NPGA3, and NP treatments also resulted in lower susceptibility to WD compared to CONT and GA3. The results highlight the positive effect of seed priming on plant response to WD, which was enhanced by the use of nanoencapsulated GA3.

Residual brewer’s Saccharomyces cerevisiae yeasts as biofertilizers in horticultural seedlings: towards a sustainable industry and agriculture

The food industry generates substantial amounts of organic waste often underutilized within the system. Craft beer production, experiencing global rapid expansion, contributes to this waste stream with byproducts such as spent grain, trub, and yeast. Many craft beer industries discharge yeast residue directly into public water bodies. In recent years, yeasts have garnered attention for their potential to enhance plant growth and contribute to sustainable agriculture. This study focuses on characterizing Saccharomyces cerevisiae yeast collected at the end of the craft beer fermentation process. Biomass characterization was conducted, and the yeast’s effect on lettuce and tomato seeds and seedlings was evaluated at four concentrations (105, 106, 107, and 108 cells mL−1) in sterile substrate. After 28 days, plant height, leaf number, fresh and dry weights of both aboveground and root parts, as well as chlorophyll content, were analyzed. The most effective concentration (107 cells mL−1) was applied to tomato seedlings in sterile substrate, compared with a commercial organic fertilizer. After 21 days, growth parameters were assessed. The study demonstrated that increasing yeast doses up to 108 cells mL−1 positively affects seed germination and seedling development. Notably, a dose of 107 cells mL−1 proved effective for application in seedlings as an organic amendment and substitute for commercial products. This integrated approach showcases the potential of yeasts in sustainable agriculture, utilizing byproducts from the food industry to enhance crop performance and mitigate environmental pollution.

The re-establishment of desiccation tolerance in germinated tomato (Solanum lycopersicum) seeds

Abstract Desiccation tolerance (DT) of seeds, one of the plant's environmental adaptation mechanisms, allows them to survive as seeds in a quiescent state under extremely water-deficient conditions during the plant's life cycle, followed by seed germination and seedling establishment under favourable water conditions. The seed-DT is lost after radicle emergence; however, there is a developmental period called the ‘DT window’ during which the germinating seeds can re-induce DT following a cue from their ambient low water potential (i.e. mild osmotic stress). The DT re-inducibility within the DT window has been used as a model biosystem for understanding molecular mechanisms that activate/supress DT in a number of plant species. However, the characteristics of the DT window for species particularly important to the agroindustry are still largely fragmented. Here, physiological analyses were performed, aiming to elucidate the properties of the DT window in tomato, a model species for Solanaceae, holding a key strategic position for the seed industry and commercial use around the world. We revealed that (i) the DT window of tomato seeds is closed when the developing radicle reaches about 4 mm after germination, (ii) the most effective ambient water potential to re-induce DT into seeds is about −1.5 MPa and (iii) there is organ specificity of DT re-induction with hypocotyls, showing a longer DT window than cotyledons and roots in post-germination seeds.

In and out Beauty and Sensitive Skin, a Psychophysiological Exploration: Myth or Reality?

Knowing that biomolecules, such as β-amyrin and α-amyrin, have some pharmacological effects, the aim of this study was directed towards exploring the protective effect of Tomato Peel and Seed Extract (TPSE) for its soothing function but also for its capacity to modulate the adrenal axis, which is involved in stress response. Ex vivo tests were carried out on skin explants to evaluate the effectiveness of TPSE formulated at 0.5% on Calcitonin Gene-Related Peptide (CGRP) and IL-10 release, Kappa Opioid Receptor (KOR), and Caspase 14 expression. An in vivo study combined a clinical evaluation of skin homogeneity and psychological parameters as well as an analysis of salivary cortisol and dehydroepiandrosterone concentrations. All measurements were carried out at the beginning and after 28 days of applying a TPSE face cream. TPSE regulated not only the release of CGRP, IL-10, and the expression of Caspase 14, reflecting anti-neurogenic and anti-inflammatory properties, but also modulated KORs. Twenty-eight days of TPSE application induced a significant decrease in intensity and extent erythrosis, a lower output of salivary cortisol, and a significant increase in pleasant emotions when compared to placebo. These results provide encouragement to continue exploring the impact of cosmetic ingredients on psychophysiological parameters to improve skin health and well-being.

Physiological and agronomical traits effects of titanium dioxide nanoparticles in seedlings of Solanum lycopersicum L

BackgroundTitanium dioxide nanoparticles (TiO2 NPs) have been reported to have contrasting effects on plant physiology, while their effects on sugar, protein, and amino acid metabolism are poorly understood. In this work, we evaluated the effects of TiO2 NPs on physiological and agronomical traits of tomato (Solanum lycopersicum L.) seedlings. Tomato seeds were treated with TiO2 NPs (1000 and 2000 mg L− 1), TiO2 microparticles (µPs, 2000 mg L− 1) as the size control, and ultrapure water as negative control.ResultsThe dry matter of stems (DMs), leaves (DMl) and total dry matter (DMt) decreased as particle concentration increased. This trend was also observed in the maximum quantum yield of light-adapted photosystem II (PSII) (Fv´/Fm´), the effective quantum yield of PSII (ΦPSII), and net photosynthesis (Pn). The concentrations of sugars, total soluble proteins, and total free amino acids were unaffected, but there were differences in the daily dynamics of these compounds among the treatments.ConclusionOur results suggest that treating tomato seeds with TiO2 might affect PSII performance, net photosynthesis and decrease biomass production, associated with a concentration- and size-related effect of TiO2 particles.

Tomato and Pepper Seeds as Pathways for the Dissemination of Phytopathogenic Bacteria: A Constant Challenge for the Seed Industry and the Sustainability of Crop Production

The seed industry plays a crucial role in global food production but it faces a persistent challenge in ensuring the health and quality of seeds, particularly those of tomato and pepper seeds, which represent key seed commodities on the global market. Seeds can serve as potential pathways for the introduction and dissemination of seed-borne bacteria, which may have devastating effects on crop yield, farmers’ remunerability, and food security. Therefore, fungicides and other antimicrobial compounds are extensively used to disinfect the seeds, thus increasing the input of chemicals in the agri-environment. In this review, we address aspects that connect disease epidemiology with seed infection and health, including seed contamination, endophytic colonization, and seed-borne infections. We focused on the main bacterial diseases affecting tomato and pepper seeds by discussing their official seed testing methods as requirements supporting a smooth seed trade. Moreover, we present a survey on the past and recent innovations for seed treatments, focusing on sustainable disinfection methods. Therefore, this review will be a short but indispensable guide for seed technologists and pathologists involved in the production of high-quality seeds, providing indications and suggestions to contrast seed-borne pathogen dissemination and avoid international controversies and complaints by phytosanitary authorities, extension services, and farmers.

Potassium Solubilizers, Aspergillus sp. and Trichoderma sp. Promote Growth in Tomato


 
 
 Potassium (K) is the third most significant plant macronutrient that plays a crucial role in growth and development of plants. K is abundant in soil, but 90-98% of K exists as insoluble minerals and only 1-2% becomes available to the plants. Certain microbes, K solubilizing microbes (KSMs), can solubilize unavailable forms of K and making it available to plants. The objective of the current study was to evaluate the growth promotion ability of two previously (2019) isolated KSMs, Aspergillus sp. and Trichoderma sp in-vitro and under greenhouse conditions using feldspar as the K source. Khandeparkar‘s selection ratio calculated based on K solubilizing assay on Alexandrov medium showed that Aspergillus (1.72+0.16) has a higher and faster K solubilization ability than Trichoderma (1.0+0.16). Effect of KSMs was assayed in a Tomato seed germination assay carried out in Petri plates with KSMs treated and non-treated soils. Both Aspergillus (58%) and Trichoderma (72%) showed enhanced percentage germination of tomato seeds under in vitro conditions compared to that of controls (Aspergillus sp.: 24%, 14%, 22.7%, 51.3%, 39.3%, Trichoderma sp.: 22%, 12%, 13%, 59%, 51%) which was statistically significant (Aspergillus, P=0.026; Trichoderma, P=0.003) at 0.05 confidence level. Seedling length (P=0.102, P=0.028) and root length (P=0.453, P=0.002) of tomato were enhanced when raised in non-autoclaved natural soil than autoclaved natural soil inoculated with Aspergillus and Trichoderma respectively. The greenhouse experiment was carried out with same experimental set up as an in vitro assay. No significant difference was observed in shoot length, number of leaves and length of leaves of tomato plants planted in soil treated with Aspergillus (P=0.093, P=0.906, P=0.260) and Trichoderma (P=0.334, P=0.239, P=0.243) respectively in comparison to controls during the vegetative stage (2 months after sawing). However, flowering was started four days early in plants planted in non-autoclaved soil treated with Aspergillus sp. suggesting that the impact of Aspergillus sp. starts to become visible in the reproductive stage. The results suggest that K solubilizing ability of Aspergillus sp. and Trichoderma sp. seem to show a positive effect on germination ability of tomato, however, only Aspergillus sp. seems to have a positive effect on the later stages of plant growth where K is mainly needed for flower and fruit development. Therefore, Aspergillus sp. can be a potential candidate to be used in up scaling the natural K fertilizers such as feldspar after intensive future experimentation.
 Keywords: Plant Growth Promoting Microbes (PGPMs), Growth promotion, K deficiency
 
 

Biogenic silver nanoparticles derived from the marine brown algae Iyengaria stellata for plant growth promotion under saline conditions.

In the green approach for nanoparticle synthesis, biomolecules like phenols, alkaloids, proteins, enzymes, and lipids are the prime reducing and stabilizing agents. In this study, we reported the synthesis of silver nanoparticles (AgNPs) using the aqueous extract of the marine algae Iyengaria stellata (Børgesen) for the first time. The characterization study showed that the developed AgNPs were spherical in shape and their average particle size was 60 nm. The UV-visible spectrum of AgNPs showed strong surface plasmon resonance (SPR) near 425 nm, whereas the Fourier transform infrared spectroscopy (FTIR) spectrum revealed the presence of several functional groups like amines, nitriles, hydroxyl, and carbonyl groups on the nanoparticle surface, which confirms the involvement of algal metabolites in the reduction and stabilization of AgNPs. The X-ray diffraction (XRD) analysis provided information about the crystallinity of developed nanoparticles, and the crystallite size of AgNPs was calculated to be 33 nm using the Scherrer equation. The algal synthesized AgNPs examined for their impact on growth of tomato seeds under salt stressed conditions showed significant enhancement in growth parameters like leaf area, shoot height, root length, shoot weight, and root weight. Also, a reduction in biochemical stress responses such as chlorophyll content, relative water content, electrolyte leakage, hydrogen peroxide (H2O2) content, glycine betaine content, and proline content was seen. This study suggests that algal synthesized AgNPs can reduce the effect of salt stress in tomato plants and promote their overall growth.